Internal combustion engine



March 24, 1942. M. Vl.. WHITFIELD INTENNAL ooMBUsTroN ENGINE liledv June 9, 1941 i Wzl/ 79. 7.

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Patented Mar. 24, 1942 INTERNAL COMBUSTION ENGINE Marcy L. Whitfield, deceased, late of Mount Gilead, Ohio, by Lellia L. Williams, administratrix, Clearwater, Fla., assignor to Lellia L.

Williams, Clearwater, Fla.

Application June 9, 1941, Serial No. 397,329

8 Claims.

y This invention relates to an internal combustion engine of the compound type and to a method of operating same wherein the fuel mixture is ignited and the products of combustion partially expand in a high pressure cylinder and then are passed to a low pressure cylinder for further expansion to perform additional work on the piston of the low pressure cylinder.

A compound four-cycle engine of the type described above is disclosed in the patent of Marcy L. Whiteld No. 2,232,579, in which the high pressure cylinder comprises a cylinder Wall which reciprocates about a stationary cylinder head which forms one end of the high pressure cylinder. The reciprocating cylinder Wall is connected to the piston on the low pressure cylinder, a portion of which forms the other and movable end of the high pressure cylinder. Thus, the piston of the low pressure cylinder and the cylinder wall of the high pressure cylinder reciprocate as a unit. The reciprocating cylinder wall is suitably connected to the crank shaft of the engine for the transmission of power thereto. In the engine of the aforesaid patent, two of the four strokes of each cycle are power strokes.

The present invention is an improvement on the engine described in the aforesaid patent and comprehends a four-cycle engine in which the eiiiciency is greatly increased by making three of the four strokes of each cycle power strokes, and obtaining the eiect of four power strokes on each cycle.

According to the present invention, the two power strokes of the engine of the aforesaid patent are supplemented by a steam stroke and by a vacuum stroke, both of which are imparted to the piston ofthe low pressure cylinder. Thus, for each cycle the piston of the high pressure cylinder of the present invention has one working or power stroke due to the initial expansion of the combustion gases inthe high pressure cylinder, and the piston in the low pressure cylinder has three working or power strokes, one as the result of further expansion of the products of combustion in the low pressure cylinder, one under the influence of the expansion of steam introduced into the low pressure cylinder, and one due to the creation of a vacuum in the low pressure cylinder.

In accordance with the preferred embodiment of the invention, the combustible fuel mixture is introduced into the high pressure cylinder on the intake stroke of the engine and simultaneously therewith the products of combustion from the preceding cycle are exhausted from the low pressure cylinder. Onthe following, or compression stroke, the combustible fuel mixture is compressed in the high pressure cylinder While steam is admitted into the low pressure cylinder 0n that side'of the piston therein which causes it and the high pressure -cylinderv wall to move in a direction to compress the combustible mixture in the high pressure cylinder.

On the third stroke, the combustible fuel mixture in the high pressure vcylinder is ignited and the cylinder wall of the high pressure cylinder, and the piston of the .low pressure cylinder connected thereto, moveunder the influence of the expansive force of the products of combustion in the high pressure cylinder to give the main power stroke. Simultaneously, communication is established between the end of the 10W pressure cylinder containing the steam previously introduced therein and a condenser to which the steam is exhausted. The condensation of the steam in the condenser creates a vacuum which is effective on the piston of the low pressure cylinder and produces a vacuum stroke which supplements the main power stroke of the high pressure cylinder. At the'end of the third stroke communication is established between the high pressure cylinder and the low pressure cylinder for the passage of the products of combustion into the low pressure cylinder so that on the fourth stroke power is imparted to the piston ofthe low pressure cylinder by further expansion of the products of combustion in the low pressure -cylinder while the products of combustion in the high pressure cylinder are exhausted. The cycle then repeats itself.`

The invention willbe described in more detail in connection with the accompanying drawing, but it is to be understood that such further showing is by way of exemplincation and that the invention is 'not limited thereto, except to the extent that it is dened in the appended claims.

In the drawing:

Fig. 1 is a vertical sectional view through an internal combustion engine embodying the invention with parts shown in elevation and partly broken away; and e v Fig. 2 is a diagram representing the cycle of each cylinder with relation to the other.

Referring to the drawing, the engine is of the type described in the' aforesaid Whitfield patent to which reference is here made for a more detailed description of those parts with which the present invention is not particularly concerned. The engine comprises a high pressure cylinder I and a low pressure cylinder 2. The high pressure cylinder includes a stationary cylinder head 3 which forms one end of the cylinder, about which a cylindrical wall 4 reciprocates. The lower end of the reciprocating cylinder 4 is connected by Wrist pins 5 and cross arms 6, which straddle a lintel member I, to the crank shaft, not shown.

Fuel and air are introduced through the tubular stem 8 and turbulator 9 into the high pressure combustion chamber I8 from the lower end as described in the aforesaid Whiteld patent.

The upper end of the reciprocating cylinder wall 4 is formed integrally with a piston II, the central portion of which forms the upper and movable end of the high pressure cylinder. The piston II is reciprocable in the low pressure cylinder 2, and being formed integrally with the cylinder wall 4 of the high pressure cylinder, the piston II and the cylinder wall 4 reciprocate together as a unit. A chamber I2 is formed at the upper end of the high pressure cylinder and has a port I3 at its upper end so that communication constantly is establishedv between the chamber I2 and the upper side of the low pressure cylinder. The lower side of the chamber I2 is provided with a valve seat I4 for a high pressure exhaust valve I5 which controls the passage of the products of combustion from the high pressure cylinder to the chamber I2, and consequently to the low pressure cylinder 2. The high pressure exhaust valve I5 is mounted in a crown I6 formed as an extension on the upper side of the chamber I2. The crown I9 has suitable frictional braking mechanism to hold the valve to any position to which it may be moved. The stem II of the valve I5 extends slightly above the upper end of the crown I6v and terminates in a iiat surface I8 adapted operatively to be engaged by a tappet I9 at the end of an upward power stroke.

Products of combustion are exhausted from the low pressure cylinder through a low pressure exhaust valve 29 extending through a chamber 2| which connects an extension 22 of the low pressure cylinder with the exhaust pipe 23. The manner in which the high pressure and low pressure exhaust valves are operated will be described later.

Water jackets are provided for cooling both the high pressure and the low pressure cylinders. The low pressure cylinder is surrounded by a water jacket 24 which is connected by conduit 25 and passages through the lintel member 1 to a water jacket 26 in the stationary cylinder head 3. Water from the water jacket 24 after circulating through the stationary cylinder head, passes out through the lintel member I to conduit 2'I and pump 23 and to a radiator 29 from which it passes through conduit 39, branch conduit 3| and opening 32 back to the water jacket 24 surrounding the low pressure cylinder.

The head 33 of the low pressure cylinder has an extension 34 projecting downwardly into the low pressure cylinder around the crown IB. The extension34 is cored to provide a steam generating space 35. Water for vaporization into steam is introduced into the steam space 35 from the cooling water system through an extension 39 of conduit 39 and inlet 3l. A pump unit 38, of standard construction, controls the ow of water to the steam generating space. Steam passes from the steam space 35 by way of conduit 39 to a steam dome 41) surrounding the exhaust pipe 23, which causes superheating of the steam.

Steam passes from the upper side of the steam dome 49 into conduit 4I to a two-way rotary plug valve 42 and through passage 43 therethrough, when the valve is in the position shown in Fig. 1, and port 44 into the low. pressure cylinder 2 at the upper side of the low pressure piston II. The valve 42 also has a passage 45 extending therethrough, which is adapted to connect the port 44 with conduit 45 leading to a condenser 4'I so that steam may be exhausted from the low pressure cylinder to the condenser, where condensation of the steam causes a Vacuum which is eiective on the upper side of the low pressure cylinder. team may be exhausted from the low pressure cylinder to condenser 41 by a vacuum pump 48 driven from a cam shaft 49 by chain and sprocket, or other suitable gearing 50. Water of condensation and any uncondensed steam or gases are passed through conduit 5I to the radiator 29 or to some other point in the cooling system.

In addition to driving the vacuum pump 48, cam shaft 49, which is driven from the main crank shaft through gearing which causes it to rotate once for each cycle of the engine, or at one half the actual angular speed of the crank shaft, also forms the means for operating the low pressure exhaust valve 20, the two-way valve 42 and the mechanism-which controls the actuation of the tappet I9 for the high pressure exhaust valve.

The stem 52 of the low pressure exhaust valve 20 extends through a bearing sleeve or bushing 53 and has a cap screw 54 on its outer end. A spring 55 is interposed between the bearing sleeve or bushing 53 and the ange of the cap screw 54 so that the valve 20 normally is urged towards its seatv or closed position. A cam 56 is carried by the upper end of a sleeve BI and controls the opening and closing of the exhaust valve 23.

The rotary plug of the valve 42 is provided with upper and lower arms 57 and 58, the ends of which normally are opposite cams 59 and 6U carried by the sleeve 5I. The sleeve 6I is keyed to slide along cam shaft 49 so that if for any reason it should be desired not to use the steam and vacuum strokes, the valve 42 may be moved into a position to close the passage therethrough leading to the port 44 and the sleeve lowered to a position such that the cams 59 and 60 will not engage the arms 51 and 58 as they rotate. To permit sliding of the sleeve 6I, carrying cams 59 and 60, the lower end thereof is provided with a collar B2 which is engaged by a fork 93 having an operating handle 64 at its opposite end.

The cam 56 is, in effect, a double cam and is shaped to so control the opening and closing of the exhaust Valve 20 with the desired speed and at the proper time of the cycle of the engine, regardless of whether the engine is being operated with the steam and vacuum strokes. When the steam and vacuum strokes are not being used the valve 20 should remain open longer on both upstrokes of the piston I I.

The rotary plug valve 42 and cams 59 and 60 are illustrated merely as one Way in which communication may be established between the upper end of the low pressure cylinder, and the steam supply and the condenser, respectively, and it is to be understood, that any other suitable valve and valve actuation means may be substituted therefor.

The means for operating the tappet I9 for the high pressure exhaust valve I5 is controlled in part by mechanism operated from the cam shaft 49 and in part by additional mechanism operated by a separate cam shaft driven by the crank shaft. Such additional mechanism includes a vertically extending push rod 65 which is caused to reciprocate once for each revolution of the crank shaft by means not shown, as for example a cam shaft driven from the crank shaft. The upper end of the push rod 65 is pivotally connected at 66 to a horizontally extending rocker arm 61, pivoted at a midpoint 68 to a support 59 extending upwardly from the head 33. A screw 'I0 is locked in adjusted position in the free end of the rocker arm El opposite the upper end of the tappet I9.

The main exhaust valve I5 should open once during each cycle, that is, once during each two revolutions of the crank shaft. It has already been stated that the push rod 65 reciprocates once for each revolution of the crank shaft. Accordingly, the length of the screw I extending through the free end of the rocker arm 6l is such that swinging of the rocker arm by reciprocation of the push rod 65 will not cause the end thereof to engage the upper end of the tappet I9 and cause it to open the high pressure exhaust valve I5. In order that swinging of the rocker arm S'I may be effective to cause the tappet I9 to open the main exhaust valve I at the proper time, that is, once for each two swings of the rocker arm, or once for eachcycle of the engine, a powertransmitting member 1I, having one end pivoted to a slide bar 'I2 reciprocating in a groove or passage 'IS ina block I4 secured to the head 33, is adapted to be interposed between the end of the screw 'IB and the upper end of the tappet. The sliding bar l2 normally is urged to a position to withdraw the member II from between the screw it and the upper end of tappet i9 by a spring l5, and is moved forward,V at the proper time during the cycle to interpose the member'II between screw i0 and the tappet I9, by a cam l@ secured to the upper end of cam shaft 49.

As cam shaft i9 rotates only once for each two revolutions of the crank shaft, or once for each cycle of the engine, the cam 'i6 will cause the member?! to be moved forward and interposed between the screws 'Iii and the tappet I9 only once during each cycle of the engine. When the member II is interposed between the screw 'I0 and the tappet I9 it transmits the movement of the rocker arm and screw to the tappet and causes the high pressure exhaust valveto be opened. A spring l1 normally maintains the tappet in its upward position so that it can transmit a movement from the rocker arm and member II to open the valve E5. When the member 'II is not interposed between the screw 'IB and the tappet i ii, the upper end of the rocker arm and the screw swing free without any effect on the exhaust valve i5. The cam It is so shaped and the movements of the various parts so correlated that the high pressure exhaust valve I5 moves faster in its opening than the high pressure cylinder wall 4 and the low pressure cylinder II are moving.

In order te provide for supercharging the high pressure cylinder, the lower end of the low pressure cylinder is provided with a supercl'iargingA air inlet port '57', connected to an air inlet pipe I8 having a check valve 7S, and an air outlet port 80 which communicates with a conduit 8I for delivering supercharging air directly to the air intake for the high pressure cylinder, or to a compressed air storage tank which in turn furnishes supercharging air to the high pressure cylinder.

- From the foregoing description it will be un- TIF derstood that as the reciprocating cylinder wall 4, and the piston II of the low pressure cylinder move upwardly on the free or non-power stroke, air for combustion will be introduced into the combustion chamber II) in the manner described in the aforesaid Whitfield patent. Simultaneusly, air for supercharging purposes will be drawn into the lower end of the low pressure cylinder through the air intake port 17 by the upward movement of the piston II. The upward movement of the piston II also forces from the upper end of the low pressure cylinder the products of combustion previously introduced therein from the high pressure cylinder for further expansion.

As the reciprocating cylinder wall 4 and the piston I I begin their downward stroke, and within 10 after the piston I I reaches top dead center, the cam 59, acting on arm 51 of the valve 42, moves the rotary plug thereof to the position shown in Fig. 1 with the passage 43 therein connecting the steam dome 4l) with the upper end of the low pressure cylinder so that the downward movement of the piston is under the expansive force of the steam, thus giving a steam stroke. During the time the steam is being introduced into the low pressure cylinder, the main exhaust valvey I5 is held closed by the pressure of the compressed gases in the high pressure cylinder and the pressure on the steam does not force it open due to the fact that thecompressed gases in the combustion chamber I0 exert a greater force against the lower face of the valve and hold it closed.

When the-piston I I approaches within about one inch of its lower dead center cam 6@ acting on arm 58 of valve 42 rotates it to cut off the supply of steam tothe low pressure cylinder, and when piston I I reaches its lower dead center cam 6@ has further `rotated the valve 42 suiiiciently to cause passage 45 therein to connect port 44 with conduit 46 leading to condenser lil, and vacuum pump I8 so that steam in the upper end of the low pressure cylinder is exhausted to the condenser. f

The downward movement of the piston II forces air previously introduced into the lower end of the low pressure cylinder out through the air outlet port 8B to be used for supercharging the high pressure cylinder as described in the aforesaid patent.

As the reciprocating cylinder wall 4 and the piston II move downwardly the high pressure exhaust valve is closed, the air introduced into the combustion chamber I0 on the previous f stroke is compressed, and fuel is injected thereinto as described in said patent. The combustible mixture of' air and fuel is then ignited.

The next upward movement of the reciprocating cylinder 4 and the piston Il is under the influence of the initial expansion of the products of combustion and is the main power stroke of the engine.

During the time that the reciprocating cylinder wall 4 and the piston I I are moving upwardly on the main power stroke, the condenser 41 is in communication with the upper end of the low pressure cylinder, as described above,'so that the vacuum which is caused by the condensation of the exhaust steam in the condenser is effective on the upper side of the piston I'I and gives a vacuum stroke which supplements the main power stroke caused by the initial expansion of the products of combustion in the combustion chamber I Il.

As the piston II and the reciprocating Acylinder wall 4 start downward on the fourth stroke of the cycle, and within 5 after upper dead center, the tappet I9 is actuated as described above to open the high pressure exhaust valve I5 to permit the partially expanded products of combustion to pass into the low pressure chamber at the upper side of the piston II for further expansion. The downward movement of the piston II and reciprocating cylinder 4 is under the force of further expansion of the products of combustion in the low pressure cylinder which provides the fourth power stroke of the cycle. During such downward movement the products of combustion remaining in the combustion chamber I are expelled or pumped out through the high pressure exhaust valve I5, and as the piston Il approaches the end of its downward movement, the lower face of the high pressure exhaust valve I strikes the stationary cylinder head 3 and is nearly closed thereby. Final closing of the valve is accomplished by the compression of the gases in the high pressure cylinder I. Also, as the piston I I and the reciprocating cylinder wall 4 reach the end of their downward stroke, the low pressure exhaust valve 20 is opened by the cam 56 so that the products of combustion at the upper end of the low pressure cylinder may be exhausted on the next upward movement of the piston II. The cycle then repeats itself.

The opening and closing of the two-way valve 42 is so timed that it remains completely closed while expansion and scavenging of combustion gases is taking place in the low pressure cylinder.

Fig. 2 shows in a diagrammatic way the cycle of each cylinder and its relation to the other cylinder, as described above in detail. Inthat figure, the upper diagram or curve represents the cycle of the low pressure cylinder, while the lower diagram or curve represents the cycle of the high pressure cylinder. The curves are arranged so that when read vertically the upper curve indicates what is taking place in the low pressure cylinder on each stroke of the high pressure cylinder.

The invention as described above makes use of the heat developed by the engine for converting water into the steam to be used to furnish the steam stroke for the engine. However, if desired, the steam for the steam stroke may be furnished from a separate and independent source connected to conduit 4I leading to the two-way valve 42.

From the aforegoing it will be apparent that the engine of the present invention, while retaining all of the advantages and features of the engine of the aforesaid Whitfield patent, will develop greater power because of the supplementary steam and vacuum strokes, which actually make three of the four strokes of the cycle power strokes, and give the effect of four power strokes for each cycle, due to the fact that while the piston of the high pressure cylinder is moving on the main power stroke, under the initial expansion of the products of combustion, the piston of the low pressure cylinder is subjected to the vacuum created in the condenser by condensation of the exhaust steam and is moving on a vacuum stroke.

What is claimed is:

1. An internal combustion engine comprising a high pressure cylinder and a low pressure cylinder, the high pressure cylinder including a stationary cylinder head and a cylinder wall mounted for reciprocation about said stationary cyl- F inder head, the stationary cylinder head and the reciprocating cylinder wall forming between them a combustion chamber, the reciprocating cylinder wall being movable under the expansive force of the products of combustion to transmit power to the power output member of the engine, a piston in the low pressure cylinder connected to the reciprocating cylinder wall of the high pressure cylinder so that they reciprocate as a unit, means for conducting products of combustion from the combustion chamber, after initial expansion therein, to the low pressure cylinder for further expansion against the piston therein, a source of steam and means for introducing steam into the low pressure cylinder to expand against the piston to give a steam stroke.

2. An internal combustion engine comprising a high pressure cylinder and a low pressure cylinder, the high pressure cylinder including a stationary cylinder head and a cylinder wall mounted for reciprocation about said stationary cylinder head, the stationary cylinder head and the reciprocating cylinder wall forming between them a combustion chamber, the reciprocating cylinder wall being movable under the expansive force of the products of combustion to transmit power to the power output member of the engine, a piston in the low pressure cylinder connected to the reciprocating cylinder wall of the high pressure cylinder so that they reciprocate as a unit, means for conducting products of combustion from the combustion chamber, after initial expansion therein, to the low pressure cylinder for further expansion against the piston therein, a source of steam, means for introducing steam into the low pressure cylinder to expand against the piston therein to give a steam stroke, a condenser, means for exhausting steam from the low pressure cylinder to the condenser for condensation therein, with resultant formation of a vacuum, and means for making the vacuum formed by the condensation of steam in the condenser effective on the piston-of the low pressure cylinder to give a vacuum stroke.

3. An internal combustion engine comprising a high pressure cylinder and a low pressure cylinder, the high pressure cylinder including a stationary cylinder head and a cylinder wall mounted for reciprocation about said stationary cylinder head, the stationary cylinder head and the reciprocating cylinder wall forming between them a combustion chamber, the reciprocating cylinder wall being movable under the expansive force of the products of combustion to transmit power to the power output member of the engine, a piston in the 10W pressure cylinder connected to the reciprocating cylinder wall of the high pressure cylinder so that they reciprocate as a unit, means for conducting products of combusvtion from the combustion chamber, after initial expansion therein, to the low pressure cylinder for further expansion against the piston therein, a source of steam, and means for introducing steam into the low pressure cylinder simultaneously with the compression stroke of the high pressure cylinder, so that said steam will expand in the low pressure cylinder to give a steam stroke.

4. An internal combustion engine comprising a high pressure cylinder and a low pressure cylinder, the high pressure cylinder including a stationary cylinder head and a cylinder wall mounted for reciprocation about said stationary cylinder head, the stationary cylinder head and the reciprocating cylinder wall forming between them a combustion chamber, the reciprocating cylinder wall being movable under the expansive force of the products of combustion to transmit power to the power output member of the engine, a piston in the low pressure cylinder connected to the reciprocating cylinder wall of the high pressure cylinder so that they reciprocate as a unit, means for conducting products of combustion from the combustion chamber, after initial expansion therein, to the low pressure cylinder for further expansion against the piston therein, a source of steam, means for introducing steam into the lowpressure cylinder simultaneously with the compression stroke of the high pressure cylinder so that the steam will expand in the low pressure cylinder to give a steam stroke, a condenser, means for exhausting steam from the low pressure cylinder to the condenser for condensation therein, with resultant formation of a vacuum, and means for making the vacuum formed by the condensation of steam in the condenser erective on the low pressure cylinder simultaneously with, and to supplement the power stroke of the high pressure cylinder.

5. An internal combustion engine comprising a high pressure cylinder and a low pressure cylinder, the high pressure cylinder including a stationary cylinder head and a cylinder wall mounted for reciprocation about said stationary cylinder head, the stationary cylinder head and the reciprocating cylinder wall forming between them a combustion chamber, the reciprocating cylinder wall being movable under the expansive force of the products of combustion to transmit power to the power output member of the engine, a I:

piston in the low pressure cylinder connected to the reciprocating cylinder wall of the high pressure cylinder so that they reciprocate as a unit, means for conducting products of combustion from the combustion chamber, after initial expansion therein, to the low pressure cylinder for further expansion against the piston therein, a steam generating space surrounding one of said cylinders and adapted to absorb heat therefrom for evaporating water in said space, and a conduit for conducting steam from said space to the low pressure cylinder to expand against the piston therein.

6. An internal combustion engine comprising a high pressure cylinder and a low pressure cyly inder, the high pressure cylinder including a staformed by the condensation of steam in the condenser eiective on the piston of the low pressure cylinder to give a vacuum stroke, and means operated from the power output member of the engine .for controlling communication from the steam generating space to the low pressure cylinder and from the low pressure cylinder to the condenser. v

7. An internal combustion engine comprising a stationary cylinder head for a high pressure cyl-y inder, a cylinder wall for the high pressure cylinder reciprocable about the stationary cylinder head, a low pressure cylinder in tandem with said highpressure cylinder, a piston in the low pressure cylinder, the piston in the low pressure cylinder being integrally connected with the reciprov cating cylinder wall and forming the movable end tionary cylinder head and a cylinder wall mountf ed for reciprocation about said stationary cylinder head, the stationary cylinder head and the reciprocating cylinder wall forming between them l a combustion chamber, the reciprocating cylinder wall being movable under the expansive force of the products of combustion to transmit power to the power output member of the engine, a piston in the low pressure cylinder connected to the reciprocating cylinder wall of the high pressure cylinder so that they reciprocate as a unit, means for conducting products of combustion from the combustion chamber, after initial expansion therein, to the low pressure cylinder for further expansion against the piston therein, a steam generating space surrounding one of said cylinders and adapted to absorb heat therefrom for evaporating water in said space, a conduit for conducting steam from said space to the low pressure cylinder to expand against the piston therein, a condenser, means for exhausting steam from the low pressure cylinder to the condenser for condensation therein, with resultant formation of a vacuum, means for making the vacuum of the high pressure cylinder, said piston having a passage therethrough for passing products of combustion from the highy pressure cylinder to the low pressure cylinder, an exhaust valve controlling the passage cf products of combustion from the high pressure cylinder to the low pressure cylinder, means operated from the power output member of the engine for opening said exhaust valve,.after initial expansion of the products of combustion in the high pressure cylinder, to permit the products of combustion to pass into the low pressure cylinder for further expansion against the piston therein, a source of steam, means for introducing steam from said sourcey into the low pressure cylinder to expand therein against said piston to give a steam stroke, and means operated from the power output member for controlling the passage of steam from the steam source to the low pressure cylinder.

8. An internal combustion engine comprising a stationary cylinder head for a high pressure cylinder, a cylinder wall for the high pressure cylinder reciprocable about the stationary cylinder head, a low pressure cylinder in tandem with said high pressure cylinder, a piston in the low pressure cylinder, the piston in the low pressure cylinder being integrally connected with the reciprocating cylinder wall and forming the movable end of the high pressure cylinder, said piston having a passage therethrough for passing products of combustion from the high pressure cylinder to the low pressure cylinder, an exhaust Valve controlling the passage of products of combustion from the high pressure cylinder to the low pressure cylinder, means operated from the power output member of the engine for opening said exhaust valve, after initial expansion of the products of combustion in the high pressure cylinder, to permit the products of combustion to pass into the low pressure cylinder for further expansion against the piston therein, a source of steam, means for introducing steam from said source into the low pressure cylinder to expand therein against said piston to give a steam stroke, means operated from the power output member for controlling the passage of steam from the steam source to the low pressure cylinder, a condenser, means for exhausting steam from the low pressure cylinder to the condenser for condensation therein, with resultant formation of a vacuum, and means for making the vacuum formed by the condensation of steam in the condenser eiective on the piston of the low pressure cylinder to give a vacuum stroke.

LELLIA L. WILLIAMS, Administratri of the Estate of Marcy L. Whitfield, Deceased. 

